This invention relates generally to magnetic data storage systems, more particularly to magnetoresistive read heads, and most particularly to structures incorporating an insulating barrier, as well as methods for making the same.
Magnetic disk drives are used to store and retrieve data for digital electronic apparatuses such as computers. In FIGS. 1A and 1B, a magnetic disk data storage system 10 includes a sealed enclosure 12, a disk drive motor 14, and a magnetic disk, or media, 16 supported for rotation by a drive spindle S1 of motor 14. Also included are an actuator 18 and an arm 20 attached to an actuator spindle S2 of actuator 18. A suspension 22 is coupled at one end to the arm 20, and at its other end to a read/write head or transducer 24. The transducer 24 typically includes an inductive write element with a sensor read element (which will be described in greater detail with reference to FIG. 2A). As the motor 14 rotates the magnetic disk 16, as indicated by the arrow R, an air bearing is formed under the transducer 24 causing it to lift slightly off of the surface of the magnetic disk 16, or, as it is sometimes termed in the art, to xe2x80x9cflyxe2x80x9d above the magnetic disk 16. Alternatively, some transducers, known as xe2x80x9ccontact heads,xe2x80x9d ride on the disk surface. Data bits can be read along a magnetic xe2x80x9ctrackxe2x80x9d as the magnetic disk 16 rotates. Also, information from various tracks can be read from the magnetic disk 16 as the actuator 18 causes the transducer 24 to pivot in an arc as indicated by the arrows P. The design and manufacture of magnetic disk data storage systems is well known to those skilled in the art.
FIG. 2A depicts a magnetic read/write head 24 including a substrate 25 above which a read element 26 and a write element 28 are disposed. Edges of the read element 26 and write element 28 also define an air bearing surface ABS, in a plane 29, which can be aligned to face the surface of the magnetic disk 16 (see FIGS. 1A and 1B). The read element 26 includes a first shield 30, an intermediate layer 32, which functions as a second shield, and a read sensor 34 that is located within a dielectric medium 35 between the first shield 30 and the second shield 32. The most common type of read sensor 34 used in the read/write head 24 is the magnetoresistive (AMR or GMR) sensor which is used to detect magnetic field signals from a magnetic medium through changing resistance in the read sensor.
The write element 28 is typically an inductive write element which includes a first pole 38 and the intermediate layer 32, which functions as a second pole. A second pole pedestal 42 is connected to a second pole tip portion 45 of the second pole. The first pole 38 and the second pole 32 are attached to each other by a backgap portion 40, with these three elements collectively forming a yoke 41 with the second pole pedestal 42. The area around the first pole tip portion 43 and a second pole tip portion 45 near the ABS is sometimes referred to as the yoke tip region 46. A write gap 36 is formed between the first pole 38 and the second pole pedestal 42 in the yoke tip region 46. The write gap 36 is filled with a non-magnetic electrically insulating material that forms a write gap material layer 37. This non-magnetic material can be either integral with (as is shown here) or separate from a first insulation layer 47 that lies between the first pole 38 and the second pole 32, and extends from the yoke tip region 46 to the backgap portion 40.
Also included in write element 28 is a conductive coil layer 48, formed of multiple winds 49. The conductive coil 48 is positioned within a coil insulation layer 50 that lies below the first insulation layer 47. The first insulation layer 47 thereby electrically insulates the coil layer 48 from the second pole 32, while the coil insulation layer 50 electrically insulates the winds 49 from each other and from the second pole 38. In some prior art fabrication methods, the formation of the coil insulation layer includes a thermal curing of an electrically insulating material, such as photoresistive material. However, when this process is performed after the formation of the read sensor, the magnetic properties of the read sensor can be permanently and undesirably altered. Thus, the formation of the coil layer 48 and the coil insulation layer 50 before formation of the read sensor can help to avoid such damage to the read sensor during fabrication.
More specifically, an inductive write head such as that shown in FIG. 2A operates by passing a writing current through the conductive coil layer 48. Because of the magnetic properties of the yoke 41, a magnetic flux can be induced in the first and second poles 38, 32 by a write current passed through the coil layer 48. The write gap 36 allows the magnetic flux to fringe out from the yoke 41 (thus forming a fringing gap field) and to cross a magnetic recording medium that is placed near the ABS.
As a current is passed through, the coil layer 48 can increase in temperature. Heat can then transfer to other components of the read/write head 24, for example the read sensor 34. With sufficiently high heating of the read sensor 34, the magnetic properties of the read sensor 34 can undesirably change, thereby adversely affecting the read capabilities during such heating. Further, this heating can thermally damage the read sensor 34, including undesirably permanently altering the read capabilities of the read sensor.
A critical parameter of a magnetic write element is a trackwidth of the write element, which defines track density. For example, a narrower trackwidth can result in a higher magnetic recording density. The trackwidth is defined by geometries in the yoke tip portion 46 at the ABS. These geometries can be better understood with reference to FIG. 2B. As can be seen from this view, the first and second poles 38, 32 can be wider in the yoke tip portion 46 (see FIG. 2A) than the second pole pedestal 42. In the shown configuration, the trackwidth of the write element 28 is defined by the width WP2P of the second pole pedestal 42. However, control of the second pole pedestal width WP2P can be limited by typical fabrication processes. More specifically, these dimensions can be difficult to control when the second pole pedestal 42 is formed over a substantially non-planar topography that includes the elements that were formed before the second pole pedestal 42. For example, the definition of the second pole pedestal width WP2P, for example including photoresistive material (xe2x80x9cphotoresistxe2x80x9d) deposition and etching, can be decreasingly reliable and precise with increasing topography. When demand for higher density writing capabilities drives smaller trackwidths, this aspect of fabrication becomes increasingly problematic. For example, the width WP2P can be limited to a minimum of about 0.4 microns for 35 Gb/in2 magnetic recording.
Thus, what is desired is a write element that is magnetically and thermally more efficient, and that has minimal adverse impact on a read sensor when combined with a read element to form a read/write head. Further, it is desired that fabrication of such a write element and read/write head be inexpensive, quick, and simple.
The present invention provides a magnetic recording device and method for making the same that provides high recording performance. More specifically, a write element having high thermal and magnetic efficiency is provided.
In an embodiment of the present invention a device for exchanging data with a magnetic medium includes a substrate and a first pole formed of ferromagnetic material and disposed above the substrate. A second pole formed of ferromagnetic material is disposed above the substrate. The first and second pole each have an edge that forms an air bearing surface. The device also includes a coil layer that is recessed into the first pole and a write gap layer formed of non-magnetic, electrically insulating material. The write gap layer is disposed between the first pole and the second pole, and the write gap layer has an edge that forms the air bearing surface. The device further includes a coil separation layer formed of non-magnetic, electrically insulating material and disposed between the coil layer and the second pole. The substrate can include a material having a high thermal conductivity such as aluminum nitride (AlN) or silicon nitride (Si3N4). In additional aspects of the present invention, such a device can be further incorporated with other components to form a read/write slider, a head gimbal assembly (HGA), a disk drive system, or any combination or permutation thereof. For example, the device can be connected with a read element that includes a read sensor, to form a read/write head.
In another embodiment of the present invention, a method of forming a device for exchanging data with a medium includes providing a substrate and forming a first pole above the substrate. The method also includes forming a coil layer that is recessed into the first pole. This includes forming a plurality of coil turns that are electrically connected to each other in series in a longitudinal direction, and electrically insulating the coil turns from each other in a transverse direction. In addition, the coil layer is formed to carry a current along a length of each turn to a next turn in series, and electrically insulated to substantially avoid passing a current transversely between turns. The method further includes electrically insulating the coil layer from the first pole and forming a second pole above the first pole and above the coil layer. Also, electrically insulating said coil layer from said second pole and electrically and magnetically insulating a first pole tip region of the first pole from a second pole tip region of the second pole are included in the method. This method and other alternative methods of the present invention can include one or more planarizations.
With the coil layer recessed into the first pole, a current passed through the coil layer can produce a stronger gap field than in the prior art. Further, when the pole in which the coil layer is embedded is proximate a highly thermally conductive material, for example an undercoat or a substrate wafer, heating of other components by the coil layer can be significantly reduced or substantially eliminated. In particular, when heating of a read sensor connected with the write element is reduced or eliminated, thermal instability and damage to the read sensor can be reduced. Also, when the surface of the write element is substantially planar when the second pole pedestal is formed, the trackwidth can be defined to be about 0.40 microns, which facilitates using the write element in high density applications, such as 35 Gbit/in2.
These and other advantages of the present invention will become apparent to those skilled in the art upon a reading of the following descriptions of the invention and a study of the several figures of the drawing.